Slag control



United States Patent 2,935,956 r a 4G CONTROL 7 Charles Gouldman Welch, Pittsburgh, Pa., assignor' of one-half to Jack F. Govanand one-half to Roy H. Govan, both of Hoboken, NJ.

No Drawing. Appli'cation September 22, 1954 I 1 e SerialNo.457,785

' a (cl. 11o- -1 lowers the iguition temperature of the latter, thereby facilitating-the burning and removal thereof. Although these removers do efiect a certain control of the soot and slag, the results obtained have varied, depending upon the conditions encountered. For the most part, these removers have been effective with soot removal, but; only in. isolated instances have the removers been effective in slag control and removal.

I t is an object of the present invention to provide aeomiaosition and particularly a method of procedure which results in improved control of slag formation and periodic removal from furnace walls, pipes and the I t. is-a further object of the invention to provide a new composition useful as a slageliminator or preventive. It is a still further object of the'invention toprovide a new method of using same in a furnace whereby the usual lancing treatment results in slag removal.

,Other objects and the nature and advantages of the invention will be apparent from the following description.

-.The procedure in accordance with this invention is to apply the slagremover to the exposed surfaces of a furnace where the slag ordinarily builds up. Following this application, the furnace is permitted to continue to build up slag on the coating, of slag remover, in the normal manner, during operation of the furnace. Periodically thereafter, a lancing treatment 'isap" lied'which results in a detachmentof theslag at the interface of the slag remover the-slag, thus effectively preventing build-up of sxagl; i. h. 7

ingredients of the slag remover are one ;}Thie essentia or 'more chlorides p eferably in combination with an adhesiv'e type--material that performs in this medium of extremely high temperatures, in the following proporjlyl Percent engende 50-95 Adhesive r I 5-50 {Other additives, such as borax, sulfur, ammonium, sulfateflainpblack, coal dust, charcoal, zinc, zinc oxide, lead, lead oxide, tin, antimony, aluminum, copper sulfate, tin sulfate, zinc sulfate, antimony sulfate, sodium or ponitrate, lead nitrate, potassium permanganate, manganesedioxide, sodium carbonate, calcium carbonate, magnesium carbonate, lead carbonate, and similar mate- As the chlorides, there may be utilized one or more of the following;

. Sodium chloride Ammonium chloride Potassium chloride Zinc chloride 1 Calcium chloride Nickel chloride Iron chloride Stannous chloride Copper chloride Manganese chloride Lead chloride Tin chloride Chromium chloride, and Similar chlorides.

In place ofthe chloride itself, a mixture of the metal,

or a 'salt of it other than the chloride, with another" chloride, give equally good results. For example, zinc and ammonium chloride may be added to yield a zinc chloride, Since sodiumchloride is the cheapest chloride, it is one most commonly used.

As the adhesive agent, there may be used gum arabic,

gum tragacanth, dextrine, starch, gum acacia, cedar gum, Indian gum, and the like. herein broadly includes any organic water soluble substancethat upon drying binds materials together.

Sometypical examples of compositions that can be used are:

Example I Percent Sodium chloride I 63 Zinc dust d 25 Charcoal 2 Adhesive V 10 A 1 Example 11 Sodiumj'chloride Sodium carbonate 5 Calcium carbonate 7 4 Coal dust 1 Adhesive 10 Example 111 Sodiurn'chlo'ride Potassium permanganate 4 Manganese dioxide 1 Adhesive 10 Example IV Sodium chloride Adhesive 10 I Example V Cupricv chloride 90 we e;

A 7 Example V1. Cuprous chloride 15 Lead chloride 25 Zinc chloride 50 Adhesive v l0 Example VII Sodium chloride 7 75 Lead of zinc l5 Adhesive l0 Example VIII The above examples are merely' illiisti'ative of a large number of compositions that can be used in conjunction with this method; V I V The composition to beutili'ze'd'ispre'ferably made into a solution or slurry and is sprayed wet onto the exposed.

surface of the slag in a furnace which has already been,

in operation. The CQmposition firmly adheres to the the surface while drying thereon, p is transient. Utilizing identical compositions with the omission of the adhesive does ,not give comparable results. Similarly, dry application, ,vvith and without ad-. llesive, while giving results to a d the same measure of effectiveness. p w l tion isweaker and more porous than the dense fused mass of slag layer.

Following the application'of the composition, the furaccumulate in the normalwayioverthe c This method hasbeen applied successfully in co'nj ction with fu furnace gases as fuel.

high'in entrained slag remit materials. It has isle,

been'used w'ith'equally beneficial'result's 'ifi COHJUHCtlOIl with other fuels, such as'coal, ,oil, gas and mixtures.

It is believed that layerof composition is' d'u'e'to'the slagiand composition fo'rming'a mixtureof'afiifierent 'fu'sion'poin't and a different density at the interface; layer'shows'it to be more orous *ascompared'with the dense fused slag. H

It has been noted that in normal operation of a fur,- nace,-the slag tends to'fuse and flow to the bottom in After the spray treatment in accordance ular movement, area.

The lancing step can be accomplished by steam, air or hot water under pressure. In the normal accumulation of slag in a'fur'nace, thermal shock itself is not sufnace is operated in the normal manner, permitting sla g to I H I i W 3 wh e Whe e. it mu be e:

rnaces and boilersjw'hich use steel :rriilllblasit 'Ih'e's'e'gases are known to run,

of the nterposed,

Examination r this ficient to break away theslag. However, with the weak layer of a different coeflici nt'of expansion, thermal shock does aid in the slag removal.

Utilizing the method of this invention on the checkers of an open hearth steel furnace, it has been found to ampaign life from approximately 50 heats to over 300 heats. i The method is particularly applicable in boilers where waste gases loaded withiron oxide are buried which result in the formation ofslag, v It will be obvious to those skilled in the art' that variface of said porous layer andsaid slagilaye r, saidlanciiig resulting in a more rapid and'more unifor the slag deposit due to V U amateur said porous layer.

2; A method in accordance with'claim'l wherein the material consists of a chloride salt 63%','zit ic dust25%} charcoal 2%, an'adhesive gummy material 10%, all mixed with water and capable of'being sprayedoiifo the faces when dry to form a porouslco'atin'gthereon. I

3. A method in accordance with claim 1, wherein the material consists of a chloride salt zinc dust 19%, borax 3%, sulfur 2%, an adhesive gummy margarine,

faces when dry to form a porous ticittt'iiigthereon.

References Cited in the file 'of patent" UNITED STATES VPATENTS,"

'f 'ELIIZIZ' Phegley ---J .a-, 1 z 2s mfi 11 1 .941 Talbot June 4, H595, B gss a ept- 4 199 H shma Apr-"e 31. 1915 Thompson e May 6 12%;; Aram 12 5111925 Aram .J. Mar. 9, 19-26;: McGlone May 3, 1932 Wolfe rr-f-frrr-r-ra-rr m k et SQRL 541931: C e i .Feb- .61 1945,; Harlow Dec.v 17 19.46 Walters "Mar: 2 2,"1955 FOREIGN PATENTS Great Britain 'Jan. "23} l899- Great Britain Dec. 7,-- l869 Great Britain -l -..'.l. Sept. 18, 1.899 

1. A METHOD OF REMOVAL OF RESIDUAL DEPOSITS OF SLAG THAT ACCUMULATE IN A FURNACE DURING NORMAL OPERATION, COMPRISING SPRAYING A MATERIAL ONTO THE INNER SURFACES OF SAID FURNACE WHICH ARE TO BE IN CONTACT WITH THE HOT COMBUSTION GASES, SAID MATERIAL INCLUDING AT LEAST 50% OF A CHLORIDE SALT AND AT LEAST 5% OF AN ADHESIVE MATERIAL COMBINED WITH WATER, SAID MATERIAL BEING CAPABLE OF DRYING ON SAID SURFACES TO FORM A LAYER OF MATERIAL HAVING A LOWER FUSION POINT AND BEING WEAKER AND MORE POROUS THAN THE SLAG, DRYING SAID MATERIAL TO FORM SAID POROUS LAYER, OPERATING SAID FURNACE IN A NORMAL MANNER UNTIL SLAG DEPOSITS FORM ON SAID POROUS LAYER BEYOND A PREDETERMINED THICKNESS, AND LANCING SAID INNER SURFACES UNTIL SAID BUILT-UP DEPOSIT OF SLAG BREAKS OF AT THE INTERFACE OF SAID POROU LAYER AND SAID SLAG LAYER, SAID LANCING RESULTING IN A MORE RAPID AND MORE UNIFORM REMOVAL OF THE SLAG DEPOSIT DUE TO SAID POROUS LAYER. 